Geopolymer mortars for strengthening existing reinforced concrete structures

This paper aims to investigate the suitability of geopolymer mortars for strengthening existing reinforced concrete structures. Mortars were realized by mixing carbon fly ash with sodium silicate and sodium hydroxide solutions and sand. Several mixtures were prepared by varying the molar concentration of sodium hydroxide solution. Physical and mechanical properties of the hardened mortars were evaluated after 7 and 28 days of curing at room temperature. Geopolymer mortars were then used as matrix to cast fiber reinforced geopolymer matrix (FRGM) composites, comprised of high-strength steel fibers. The composites were applied on one face of concrete prisms and the bond behavior of the FRGM–concrete joints was investigated using single–lap direct shear test setup. Results show that geopolymer mortars can potentially replace cementitious mortar used in fiber reinforced inorganic matrix composites for strengthening applications of existing reinforced concrete structures.